Samsung UN55D6900 Manuals Usually, but not always, capacitors will show visible signs of failure. There are two main types of visible failure. When it fails, the chemical reaction inside the capacitor can produce hydrogen gas, so capacitors have vents cut into the tops of their aluminum cans. These are intended to break and release the gas that has built up inside the capacitor. So, a capacitor which has failed can show bulging at the top. Below is an example. Another[…]